Gas laws identification: “The absolute pressure of a fixed mass of a perfect gas varies inversely with its volume at constant temperature.” Does this statement describe Charles’ law?

Difficulty: Easy

Correct Answer: No

Explanation:


Introduction / Context:
Several classical gas laws describe limiting relationships among p, V, and T. Correctly matching statements to their proper names avoids confusion in thermodynamics and fluid mechanics calculations.


Given Data / Assumptions:

  • Ideal gas behavior.
  • Temperature held constant (isothermal condition) in the statement.
  • Fixed mass of gas.


Concept / Approach:
The statement “pressure varies inversely with volume at constant temperature” is Boyle’s law, not Charles’ law. Charles’ law states that for a fixed mass at constant pressure, volume is directly proportional to absolute temperature (V ∝ T). Meanwhile, Gay-Lussac’s law states that at constant volume, pressure is proportional to temperature (p ∝ T). Recognizing which variable is held constant is the key to correct identification.


Step-by-Step Solution:

Identify condition: T constant ⇒ isothermal relation.Apply ideal gas law pV = nRT ⇒ with T constant, p ∝ 1/V → Boyle’s law.Therefore, the statement does not describe Charles’ law.


Verification / Alternative check:
Mnemonic: B (Boyle) links p and V; C (Charles) links V and T; G (Gay-Lussac) links p and T—each with the third variable constant.


Why Other Options Are Wrong:

  • Yes: Mislabels Boyle’s law as Charles’ law.
  • Other qualifiers: Temperature or gas type limitations are irrelevant to the naming.


Common Pitfalls:
Swapping Boyle and Charles due to both being simple proportionality laws; forgetting which variable is constant in each statement.


Final Answer:
No

More Questions from Thermodynamics

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion